Title

Author

Document Type

Thesis - University Access Only

Award Date

2013

Degree Name

Master of Science (MS)

Department

Electrical Engineering and Computer Science

First Advisor

Michael Ropp

Second Advisor

David Galipeau

Abstract

Photovoltaic generation is a sustainable but expensive technology because of the equipment required for generating electricity as compared to other alternatives. Thus, to make photovoltaics (PV) cost-competitive, it is required to maximize the overall efficiency of photovoltaic plants, which depends on the efficiencies of the PV modules, inverter, and the maximum power point tracking algorithm. The efficiency of the maximum power point tracking algorithm can be improved by updating the control algorithm in PV plants that is already in use. There are several maximum power point tracking algorithms available. Perturb and observe (P&O), and variants of it, is the most widely used method because of its simplicity, good performance and low computational demand. However, Perturb and Observe has some well-known drawbacks under rapidlychanging irradiance conditions, and there has been little study of the behavior of a fixed Perturb and Observe design when coupled to different types of PV array. Fife et al developed a new method of maximum power point tracking, called the Rate Corrected Algorithm that is designed to address the challenge of changing irradiance. The objectives of this work were to optimize the performance of a Perturb and Obseve algorithm, compare the performance of the optimized Perturb and Observe to the Rate Corrected Algorithm under rapidly changing irradiance conditions, and to examine both the Perturb and Observe and the Rate Corrected Algorithm when used with various solar cells. The two algorithms were compared using crystalline silicon (c-Si), amorphous silicon (a-Si), Cadmium Telluride (Cd-Te), Copper Indium Diselenide (CIS) and Heterojunction with Intrinsic Thin (HIT) layer solar cells. It was found that the Rate Corrected Algorithm outperformed (with the efficiency above 99% ) the Perturb and Observe for all irradiance conditions and all solar cell types, and that the type of solar cell used did make a significant difference in the MPPT performance of Perturb and Observe (95.68% to 99.39% ) but less so for the Rate Corrected Algorithm(99.22% to 99.59%). Also, both algorithms were tested under partially shaded conditions, and it was found that neither algorithm was able to track the exact maximum power point in that case. Future improvement in Rate Corrected Algorithm algorithm can be done by implementing a mechanism to track in partially shaded conditions.